A mitral valve, such as shown in FIG. 1A, including an anterior leaflet 1 and a posterior leaflet 2, is the inlet valve to the main heart pumping chamber (left ventricle 4). The mitral valve is forced to close when the ventricle 4 contracts, preventing backward flow of blood. To ensure that this valve does not prolapse backward (into left atrium 7) when the heart contracts, leaflets 1,2 are restrained by a network of tendinous chords 5 anchored to the posterior wall of the heart 6. The leaflets normally meet or coapt so that their tips are juxtaposed, along with up to one-third of their lengths, forming an effective seal 8 to prevent MR. In a variety of diseases, however, the leaflets fail to meet properly due to leaflet elongation or elongation or rupture of the chords 5. As shown in FIG. 1B, one or more leaflet portions 10 may then prolapse into the left atrium 7, reducing coaptation and creating a gap between the leaflets 1,2 that allows MR to occur (blood flow illustrated by arrows 9.). Such regurgitation can produce heart failure, rhythm disorders, sudden death, and a predisposition to lethal heart valve infections. Therapy has until now required open-heart surgery to replace the valve or repair it by approximating leaflet tips.
Alfieri, et. al, have described a possibly minimally invasive repair mechanism. As shown in FIG. 1C, a suture 12 may be placed between the tips of the leaflets 1,2 to prevent prolapse of one leaflet relative to the other. As shown in FIG. 1D, this produces a competent valve with two openings 14, one on each side of the suture 12 position. Such an orifice does not materially obstruct inflow of blood into the left ventricle.
Several approaches have been proposed to practice this repair in a minimally invasive manner. Specifically, Grimes (U.S. Pat. No. 6,312,447) teaches that a catheter, advanced across the interatrial septum into the left atrium, can grasp the leaflet tips using a suction apparatus at the end of the catheter. A fastener such as a staple or shape memory rivet is then inserted into the leaflet tips to effect the edge-to-edge closure repair.
Previous approaches employing suctioning and/or suturing of leaflet tips suffer from a number of common limitations. First and foremost, as shown in FIG. 2A, in patients with sufficient MR to warrant such procedure, the leaflets 1,2 are initially misaligned, limiting or precluding the ability of a single device 22 alone at the tip of a catheter 20, or multiple devices at a single location along the catheter center axis 11, to bring the leaflet tips, at spatially distinct positions 16 and 18, into juxtaposition in order to suture or fasten them together. Second, in order to be effective, a suction device for grabbing the leaflet tips must withdraw blood extremely rapidly. Unless blood is reinfused immediately, this can cause hypotension. Third, as illustrated in FIG. 2B, unless an additional mechanism is inserted via the aorta to stabilize leaflet surfaces 3 and 4 that are not adjacent to the suction device, a rivet or staple 15 emerging from the catheter 20 may simply displace the leaflets 1,2 from the catheter tip 22 (as shown in FIG. 2C) rather than successfully penetrate the leaflets. Fourth, approaches that employ grasping the leaflets generally do so in a plane perpendicular to the catheter, and do not provide a sufficiently large and stable leaflet surface area through which a staple or a suture can be inserted.
Thus, what is needed is a percutaneous mitral (or tricuspid) valve repair system that can overcome these and other limitations of the prior art. A single device accomplishing all of the above objectives and others is highly desirable.